Field of the Invention
The present invention relates to a power supply system.
Description of the Related Art
U.S. Pat. No. 7,408,794 and Japanese Patent Laid-Open Publication No. 2006-187147 disclose power supply systems, each including a first DC power supply and a second DC power supply, power converters each having a switching circuit for DC/AC conversion connected to each DC power supply, and a transformer provided to couple between the power converters. These power supply systems can output a voltage different from a power supply voltage by boosting or lowering the voltages from a plurality of power supplies.
The power supply systems of the prior art have difficulty in making a fine adjustment of voltage as low as about 10 V because the output voltage is changed by adjusting the duty of the switching circuit. For example, it is difficult to accurately switch between 12 V and 14 V and to output an accurate voltage.
In addition, if a fault occurs in a power converter, all functions may stop, and thus such a power supply system cannot be applied to a system requiring reliability, such as an automobile.